adding a reflector and director to a gainmaster ?

[wavrider]

The Yagi-Uda Antenna - Yagi Antennas

Notice that the reflector and director are based on resonance not length of the element.

When using a 1/2 wl dipole or folded dipole the length is an electrical 1/2 wl or full wave length thus simple math can be used to make the length of the reflector and the directors.

If using a 5/8 then every element will have to be made to resonant on the frequency needed to be a reflector or director.

I said that just making the physical length of a reflector or director 5/8 wl plus or minus 5% would not work as all elements would need to be resonant with a matching network.

As far as the 1 or 2 dbd gain. Compared to what? a 1/2 wl dipole? the 5/8 wl might have .75 to 1 dbd gain over a 1/2 wl dipole.

If the dipole is horizontal then the dipole will have more gain than the 5/8 wl if it is vertical.

As BOB said a 1.5 wl which is working off the third harmonic of the fundamental frequency has been tried. It is called a 3/2 dipole. I have used them for the Hf bands and they do work well as the major lobes come off the end of the dipole at a 30 to 45 degree angle not in a figure 8 pattern as a typical dipole.

If the 5/8 wl yagi is feasible and works better than a 1/2 wl dipole feed yagi why are there not any produced and sold?

I can not detect a 1dbd difference in any of my receivers I have if you can that is an impressive receiver.

Not a pissing contest, just a good conversation

 

[Needle Bender]

The Yagi-Uda Antenna - Yagi Antennas

Notice that the reflector and director are based on resonance not length of the element.

When using a 1/2 wl dipole or folded dipole the length is an electrical 1/2 wl or full wave length thus simple math can be used to make the length of the reflector and the directors.

If using a 5/8 then every element will have to be made to resonant on the frequency needed to be a reflector or director.

I said that just making the physical length of a reflector or director 5/8 wl plus or minus 5% would not work as all elements would need to be resonant with a matching network.

As far as the 1 or 2 dbd gain. Compared to what? a 1/2 wl dipole? the 5/8 wl might have .75 to 1 dbd gain over a 1/2 wl dipole.

If the dipole is horizontal then the dipole will have more gain than the 5/8 wl if it is vertical.

As BOB said a 1.5 wl which is working off the third harmonic of the fundamental frequency has been tried. It is called a 3/2 dipole. I have used them for the Hf bands and they do work well as the major lobes come off the end of the dipole at a 30 to 45 degree angle not in a figure 8 pattern as a typical dipole.

If the 5/8 wl yagi is feasible and works better than a 1/2 wl dipole feed yagi why are there not any produced and sold?

I can not detect a 1dbd difference in any of my receivers I have if you can that is an impressive receiver.

Not a pissing contest, just a good conversation

OK, sorry I got as little hot when you asked for the 5/8 link, because I know you know we are tossing around ideas and possibilities, not proven designs.

Perhaps, as you say, a 5/8 director wouldn't work as a director but more like a reflector based upon resonant length, but what I'm wondering about is whether or not having this newer design, a center fed 5/8 dipole as per the Gainmaster might not effect an extended 5/8 field causing/forcing the parasitic elements to re-radiate and reflect/direct, since this type of extended current distribution hasn't been tried before as a driven element.

Since the Gainmaster stretches the usual maximum 1/2 wave current node out to 5/8 long, perhaps when excited by this extended current distribution driven element with those unique current phase angles, the parasitic elements might resonate differently than they would normally and mirror the Gainmaster current distribution?

Or perhaps the parasitic elements might need similar series/parallel phasing caps in order to work as such, if those elements are going to revert back to self-resonance even in the presence of such a unique excitation as the Gainmaster driver.

And as far as the gain factor, the Gainmaster 5/8 has all current in constructive phase unlike the conventional end fed 5/8 which loses about 40% of it's current distribution due to cancellation, and has only about 1.2db gain over a 1/2 wave.
In testing against my metal bottom fed 5/8 the Gainmaster outperforms it by at least 1.5-2db so add that to the 1.2dbd and you have more like 3dbd with relation to both the driven and beam parasitic element size, not just compared to a single element dipole.

I could see this being a 3dbY antenna where Y represents a Yagi of similar number elements

If you haven't read the Sirio Gainmaster page, it deserves a look.

 

[wavrider]

I agree and I read the gain master page, it is interesting in the ability to distribute current as it does.

Would it work as a driven element? Easy way to find out is use wire as a reflector and a director.

Would take an analyzer to get the resonance correct then install the wire elements as a reflector and a director.

Now if indeed there would be an 3DBD increase in forward gain that would be outstanding.

Maybe ROBB will chime in and give his view point, he has had correspondence directly with Sirio company and may be able to shed some insight to it.

Or better yet send Sirio an email and see what they think of the possibility of making an yagi out of the gain master.

 

[Needle Bender]

I know there's a guy called Shockwave who posted about being in touch with Sirio but I didn't know Robb was too.
I wonder if the guys at Sirio bother to read this forum or any other?
I bet they're already working on one. :

 

[Marconi]

Check out the attached four Eznec monopole models from .50 to 1 wavelength, comparing the gain and angles. Then consider how much feed point transformation and associated matching losses might be required to match these antennas in a real world setting based on the Eznec Source Data for each.

I know you guys already understand how various length radiators are reported to act as a vertical monopole, but I was thinking of modeling a three element .625 wl driven element with ref/dir spacing and element lengths at 27.205 mhz, based on the Maco M103c model.

Then model the same antenna with ref/dir made using .5% of the physical length of the 5/8 wave driven element that is also being discussed and see what Eznec might suggest.

These models are for the subject of this discussion only, hopefully suggesting the trend lines that such antennas may produce. They are not matched, and no mast or feed line is included, so I can later do the beam idea in Free Space and see what that shows. The front page is the data recaped for these models.

View attachment Various radiators.pdf

I have not done the beams yet, so I'll post them later.

 

[BOOTY MONSTER]

my idea was to hopefully keep the very wide usable bandwidth of the vector but add the gain and directivity of a beam . apparently that's not a possibility ....

 

[Marconi]

my idea was to hopefully keep the very wide usable bandwidth of the vector but add the gain and directivity of a beam . apparently that's not a possibility ....

I think you meant the Gain Master here.

I commented to you earlier that my models will not indicate what the band width is unless the antenna is matched or near a match. So, I can't help you with that issue, but I suspect the .625 wave driven element would act just like the 1/2 wave and loose some of its nice, stand alone, band width when parasitic elements are closeby.

Wavrider looks to be correct, the reflector and the director have to remain at or close to resonance + or - the 5% or whatever, for them to work as intended. It seems that trying to make them physically different from a 270" inch 5/8 wave radiator just won't work.
I need to add that I'm considering the statement above as it applies to frequency being 27.205 in this case.

Here are the .50 wave like the Maco 103c, the same reflector and director with a 5/8 wave driven element, and a 5/8 wave with reflector 5% longer and director 5% shorter. I also added the Maco manual with my notes for dimensions used.

View attachment Gain Master Beam idea.pdf

Below are the antenna currents and it shows why we see the pattern results noted.

View attachment GM Beam idea Currents.pdf

 

[BOOTY MONSTER]

yes , i did mean gainmaster . thanks for the correction .

 

[Henry HPSD]

Hi marconi,

Could you be so kind and post freespace moddels instead of the "real" moddels or at least "with" them.

Im getting the impression your beam has 8,55 dBI ?
But thats far from beeing real.
Im guessing most dont realize you need to subtrackt about 6 dBI (ground gain, as your plot is over real earth) to get accurate figures..

By doing so..im guessing there is something serious wrong ?
As only 2..3 dBi remains ? Perhaps im not correctly interperating it.

A "average gain" result would be appriciated aswell as that would give a clue of how accurate the model is.


CORRECTION...I just noticed you have them vertical...so that leaves intstead of 8,5 roughly 7,2 dBI ?

Keep up the good work !

Henry

 

[Marconi]

Henry, earlier I posted that I would do free space models for this project. I will add the AG to the FS models.

Check out the attached four Eznec monopole models from .50 to 1 wavelength, comparing the gain and angles. Then consider how much feed point transformation and associated matching losses might be required to match these antennas in a real world setting based on the Eznec Source Data for each.

I know you guys already understand how various length radiators are reported to act as a vertical monopole, but I was thinking of modeling a three element .625 wl driven element with ref/dir spacing and element lengths at 27.205 mhz, based on the Maco M103c model.

Then model the same antenna with ref/dir made using .5% of the physical length of the 5/8 wave driven element that is also being discussed and see what Eznec might suggest.

These models are for the subject of this discussion only, hopefully suggesting the trend lines that such antennas may produce. They are not matched, and no mast or feed line is included, so I can later do the beam idea in Free Space and see what that shows. The front page is the data recap for these models.

View attachment 6643

I have not done the beams yet, so I'll post them later.

Nothing here was an attempt to model to specifications. I didn't tapper the elements among other things, plus I listed several things omitted in the models...things that might be considered important to the gain and maybe even to the angle to a lesser extent. I didn't even tune the 1/2 wave model to resonance, I just set the radiator to 18' feet.

Thanks for the encouragement.

 

[Henry HPSD]

Hi Marconi,!

Thanks, and it was a ment / honest "keep up the good work" !

It migth be fun to give "these" moddels a shot.

Henry

 

[Marconi]

Hi Marconi,!

Thanks, and it was a ment / honest "keep up the good work" !

It migth be fun to give "these" moddels a shot.

Henry

That would be great. I've not done too much with beams and your help would be appreciated. If you need the files, then let me know and I'll try and email them to you. I think I have your email.

Here are the free space models.

View attachment Free Space models.pdf

 

[Needle Bender]

Thanks Marconi! It looks like maybe Wavrider was right and the parasitic elements might also have to be phase aligned.
Nice work, as always!

 

[Marconi]

Thanks Marconi! It looks like maybe Wavrider was right and the parasitic elements might also have to be phase aligned.
Nice work, as always!

Well NB your right. Looks like wavrider was right on point. I didn't know what to expect, and I've never though about the point he made either. Shows me that somebody is thinking.

I sure didn't expect to see the phase shift that resulted. As generally happens with my models...I just put the dimensions in. I don't know enough to be tricky yet, but I pretty much suspect when a guy is not shooten' straight...regarding his modeling ideas.

The currents report is pretty revealing as to what happens though. I learned something again. This report is a very good demonstration of what happens with phasing...and these models very simply reveal that idea if one pays attention to the details.

Frankly I wondered what actually caused the reflector to attenuate the signals. I use to think it was like some kind of blocking deal going on, but now I can see why...it is the phasing that does it.

I kind of thought somebody would comment on the four monopoles idea I did at first, but I guess that didn't stimulate any curiousity, or understanding.

 

[wavrider]

Thanks Marconi! It looks like maybe Wavrider was right and the parasitic elements might also have to be phase aligned.
Nice work, as always!

Needle Bender thanks but it was not me being correct. Just basic antenna theory.

Example, the moon raker four antenna 1/2 wl elements except the reflector is a full wave loop.

Antennas work on frequency. The element gives an electrical length that needs to be resonant at the desired frequency for a driven element, and 5% lower and higher in freq for the reflector and director respectfully.

Not a myth just antenna theory